A friend found a stack of discarded LED assemblies in a skip, and threw them my way. Amongst the other bits, there were several Dialight Lumiled strips – nicely machined aluminium backplates with 6 bright white 1-Watt LEDs mounted on top. They’re designed to be run from a proprietary power supply that delivers around 19.2 volts at a tightly controlled 350mA. So, not the sort of thing you can wire up to a car battery.<\/p>\n
I figures this was as good a time as any to start embarking on analogue electronics – gotta dip your toe in the water at some stage. So, after several hours of wading through various “solutions” on Farnell’s website, I came across a tiny little chip that claims to be designed specifically for driving blocks of 6 LEDs like this. The datasheet showed an example circuit along with the specifications of the extra components needed, so I ordered the bits and designed a little board.<\/p>\n
It’s a boost driver, which means it can produce a higher voltage output than the voltage you put in. Power in and out are roughly the same, though; so it takes more current input than the current it can provide at the output.<\/p>\n
I designed the PCB in Eagle, and used a free plugin\/script to convert the pattern into G-code for my mill to understand. Gotta write more about my mill another time – for me, this is where it shines. It took about 5 minutes to carve out this little circuit, much much faster than etching a board in acid, the old way.<\/p>\n
Soldering the components on was a little bit fiddly but doable. I find it helps, when soldering multi-legged components like the little SOT3-6 driver chip, to wet all the pads on the board with solder first, using solder wick to remove all but the thinnest little layer.<\/p>\n![\"\"](\"https:\/\/howiem.org\/wordpress\/wp-content\/uploads\/2012\/08\/LED_PWR_PCB-004.jpg\" "\\"LED_PWR_PCB")
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